The present invention relates to a method of replacing and adjusting preprinted strip material on a manufacturing machine.
The present invention may be employed to advantage on packing machines in general and, in particular, on cigarette packing machines to which the following description refers purely by way of example.
Cigarette packing machines are known to employ, e.g. for coupons applied to the packs, preprinted strips of paper or similar printed at regular intervals with a sequence of identical graphics, each defining a coupon which is cut off the strip on the packing machine prior to being applied to the pack.
The preprinted strip is normally run off a reel which, as it is about to run out, is changed with a new one by means of splicing devices which provide for joining the end portion of the run-off strip to the lead portion of the new one, so as to make the changeover without stopping the machine. On known splicing devices, the run-off and run-on strips are usually fed along a common route portion immediately downstream from which a standby portion of variable length is provided enabling the run-off strip to be stopped along said common route portion, for adjusting the printed graphics and splicing the two stationary strips together.
One of the major drawbacks of known splicing devices of the aforementioned type is the relatively long distance covered by the strips between the reels and the user machine, and defined by said common route and standby portions, which standby portion is substantially used up at each splicing operation and, to be restored, requires that the packing machine be run at less than normal speed for a certain length of time after the strips are spliced.
Moreover, the length of said route subjects the strips to severe axial and transverse stress resulting in frequent tearing and loss of adjustment, and, in the event of the strips being torn, involves serious difficulties and relatively prolonged downtime for reassembling them.